1. Field of the Invention
This invention relates to a control device for tilting a headrest with respect to a backrest in a treatment chair whose headrest is permitted to tilt forwardly and rearwardly and to be locked in any desired position with respect to the backrest of the treatment chair.
2. Prior Art
Referring to the treatment chairs of the prior art, such as the dental treatment chair shown by way of illustration in FIG. 1, there are two types of headrests heretofore in use for supporting the head of a patient in the dental treatment chair, one being the type (FIG. 1) wherein the control device for tilting the headrest and for locking the same in the position required for treatment is located outside of the headrest, and the other being the type wherein the control device is located inside of the headrest. But in both types, the head supporting portion of the headrest had the following disadvantages when a patient underwent treatment with his head being held approximately horizontal and with the mouth open while the headrest was tilted slightly forward with respect to the backrest which was moved down to an approximately horizontal position. (FIG. 1 is a longitudinal sectional side view showing the headrest portion of a prior art treatment chair in the state described above.) As apparent from FIG. 1, a head supporting portion 7 fixed to a frame 2 connected to the rear end of a support 1 is not in close contact with the rear neck region P.sub.1 of a patient P in the position shown, and accordingly, the patient P is forced to open his mouth unnaturally with the rear head region being slightly raised and the chin down. Accordingly, the patient often experiences pain in keeping his mouth open and the operator himself is also forced to restrict the range of manipulation of an instrument or to take a forwardly inclined posture, and feels tired if the treatment takes a long time.